There are several food markets in Lisbon. The Praça da Figueira food market looked the most authentic, from the research I did. "Authentic" as in real Portuguese street food, not contrived showy stuff you can get anywhere around the world where there's a trendster buzz. Others, like TimeOut Market (apparently corporate-owned/funded by England's version of LonelyPlanet), were uber-cheesy to me. Mercado da Ribeira, and Praça dos Restauradores, are other popular food markets, fyi, but all in all, Praça da Figueira was the most real from all the docus and food shows I watched in research.
I was 5 months pregnant while in Lisbon, and if you're visiting, you know how much walking is required, and rigorous walking, with all the steps and steep hills. It was quite a hike from our hotel to get to Praça da Figueira, and we were so let down to discover they had no food tents! I don't know if it was because we visited in mid-February, and they're closed in winter? Or because it was during Carnival, and they removed the tents for the local parades? Or the time of day (late afternoon) was past closing? But there were no food tents anywhere when we were there.
We still enjoyed the festive feeling of the square, and the parade of locals plodding through with music and hollering (see my videos).
The layers of buildings climbing up the hill at one end of the square, are really amazing to see (shown in my photos), and the square is very large, so you have a distance to sightsee and people-watch.
A little history? The Praça da Figueira ("Square of the Fig Tree") is in the Baixa neighborhood. Prior to the big 1755 quake, most of the square was a hospital. The hospital was so badly damaged, they had to demolish it in 1775. It then became an open market, so is really neat to me that they continue that history with the food tent (if you visit when it's there).
They actually had a semi-permanent covered market structure from 1885-1949.
The well known bronze equestrian statue is actually relatively new, dating to 1971. It honors King John I (1357-1433), who was inaugurated in the square. The statue was off-center when I visited, and it seemed awkward to me, especially considering the centering of all other monuments in other Lisbon squares. I looked it up later, and read that it was originally in the middle of the square, but was moved off to the side in 2000, so you could see it from Praça do Comércio. That may aggrandize Praça do Comércio, but, IMO, detracts from Praça da Figueira.
It is a lively square, and when we visited, was occupied by more Lisbonites than tourists, but this may have been affected by the Carnival holiday. I definitely recommend a visit if you can figure out when those food tents are there!
A good video of the market: https://www.youtube.com/watch?v=YzDrpuaPFtw read more